CAST

CAST

Often a CAST is implicit - for example if you concatenate a string with a number the number will be automatically changed to a string. However sometimes you need to make the CAST explicit.

CAST(expr TO type)

In this example we get the population in millions by casting the floating point value to DECIMAL(8,1) - this ensures one decimal place of accuracy.
You can also CAST a date to a string to extract components using SUBSTRING or make up another date.

SELECTCAST(population/1000000ASDECIMAL(8,1))AS a
,population/1000000AS b
FROM bbc